车用热膜式空气流量计分析与设计

针对目前国内车用热膜式空气流量计设计较少的现状,以某款模拟电路样机为研究对象,在分析样机加热控制电路、检测电路及传感探头结构的基础上,对样机进行了实验。结果表明,样机能检测不同流量的气体,并具有一定的温度补偿功能。样机正确反映了热膜式空气流量计的检测原理,直观显示了探头部分结构。同时,通过实验分析了模拟控制方法、检测电阻线性度等因素对样机热区性能的影响。最后,针对模拟控制电路存在的缺陷,基于汽车芯片提出一种数字化解决方案。研究为热膜式空气流量计的设计提供了参考,具有一定的工程意义和实用价值。     

数字输出型热膜式空气流量计的设计与实现

针对目前国内数字输出型热膜式空气流量计设计较少的现状,设计了一种基于硅MEMS新型热膜式AFS07空气流量传感器和PIC16F1786微控制器的数字输出型车用空气流量计。详细分析了该空气流量计的工作原理和检测电路、恒温差控制电路的设计,通过PIC16F1786微控制器产生了ECU所需频率范围为1.8~11 k Hz、占空比50%的方波流量信号和频率为19 Hz、占空比可变的矩形波温度信号。在此基础上对样机进行了实验。实验结果表明:该样机实现了对不同流量气体和进气温度的检测,且具有良好的温度补偿功能;同时得出该空气流量计输出信号的周期与其对应信号的输出电压之间呈线性关系。     

别克汽车空气流量计故障分析与维修

针对别克汽车动力下降、油耗增大、怠速不稳等情况,对产生这些故障的原因逐条排查,最后锁定是由于空气流量计电阻丝受到空气中尘埃的污染造成的。通过清除附着在电阻丝上的污染物,是汽车功能恢复正常,圆满地解决了以上问题;同时,由于修复了故障元件,避免了更换部件总成,节省了费用。     

进气系统空气流量计布置数值研究

为揭示流场对进气系统空气流量计的影响,基于标准k-ε湍流模型,利用STAR-CCM+对不同插入角度、深度、轴向位置、管路入口圆角半径等因素影响下的空气流量计性能进行了系统研究,并与试验进行对比验证了数值方法的可行性.研究表明:插入角度和深度对速度偏差影响明显,且在高流量区,速度偏差相对更小;存在最佳插入角度和最佳插入深...     

车用膜式空气弹簧静特性试验研究

以Firestone 1T15M-2膜式空气弹簧为基础,建立了空气弹簧静特性试验测试系统,利用试验的方法获取了空气弹簧的变形量与载荷、变形量与内压、变形量与有效面积的静特性曲线.分析试验结果表明,空气弹簧静刚度随气囊内气压的增大而线性增大;膜式空气弹簧在变形较小时,其刚度基本呈线性,当变形量加大,刚度非线性明显.以空气弹簧平衡位置为中心的60mm振动行程范围内,空气弹簧有效面积基本保持不变,当弹簧变形超过此行程,弹簧拉伸阶段,有效面积迅速下降,弹簧压缩阶段,有效面积迅速增大.在同一弹簧高度下,弹簧初始内压的变化对空气弹簧有效面积的影响不大.     

论述气体涡轮流量计耐久性试验

介绍对气体涡轮流量计产品进行耐久性试验的重要性,以及相关的试验要求、试验装置、试验过程,证明该产品在预期的使用寿命期限内,能够保持其计量上的准确性。     

涡轮流量计计量液体误差的补偿方法

本文讨论了用微机实现液体计量的误差修正方法,给出了误差补偿的数学模型,与口径为10mm—80mm涡轮流计配用使计量过程中的最大相对误差修正到0.001％。     

采用雷诺数修正法的高精度气体涡街流量计的研究

文中以气体涡街流量计为例，从流体力学的角度分析了涡街流量计测量误差产生的原因，结合气体测量的特点，使用了一种工程化的解决方法。并根据应用实际，给出了精确的将工况流量转化为标况流量的软、硬件方案。     

专用车膜式空气弹簧特性研究

对专用车空气悬置进行适应性改型,根据气体状态方程,得到膜式空气弹簧刚度与固有频率的表达式,研究了膜式空气弹簧初始气压、初始容积和有效面积对刚度特性的影响。结果表明,专用车膜式空气弹簧的刚度呈非线性,其固有频率在车桥载荷变化范围内保持基本稳定,适于载荷变化大的专用车悬置使用。     

微小缝隙式层流流量计设计及测量特性研究

为解决层流流量计(LFM)线性度不佳的问题,提出了一种微小缝隙式LFM,并介绍了层流流量计的测量原理、结构设计及参数计算。对一台设计流量范围约为0～280 mL/min的试验件进行了试验,试验中使用的标准装置为活塞标准装置,合成不确定度为0.12%,扩展不确定度为0.24%(k=2)。试验结果显示,在未使用任何修正系数的前提下,试验件最大引用误差为-0.90%。试验件基本达到准确度1.0级的设计指标,量程比10∶1。此外试验件线性度优良,其Re_(max)d_e/l值为3.42,大于传统要求的2～2.5,说明此结构设计可有效克服突扩突缩带来的非线性影响。     

Theoretical and experimental investigation for developing a gas-liquid two-phase flow meter

Despite the intricacy, inline metering of two-phase flow has a significant impact in multitudinous applications including fusion reactors, oil, nuclear, and other cryogenic systems. Since measurement of individual flow rate is prominent in various systems, it warrants the establishment of a flow meter system that can monitor the mass flow rates of liquid. In this regard, an approach was taken towards the development of a two-phase flow meter system in the present study. The concept involves two-phase flow through narrow parallel rectangular channels resulting in laminar, stratified flow with a slope at the liquid-vapor interface. The height of the liquid column at specific channel locations is measured for determining the flow rate. However, the geometric configurations of the channels and fluid properties are pivotal in ensuring accurate measurement. Consequently, theoretical and experimental studies are performed to investigate the correspondence between flow rate and change in liquid height. Based on the governing equations, a theoretical model is established using MATLAB®. The model investigated the intricate influence of various flow and fluid properties in the estimation of the mass flow rate. The experimental investigation was done with various conditions under different liquid and vapor volume flow rates for validating the proposed supposition and the theoretical model. Both the theoretical and experimental analyses showed fair correspondence. The proposed system estimated the mass flow rate within a tolerance of ±10% and showed potential towards the development of the cryogenic two-phase flow meter.     

Novel mass air flow meter for automobile industry based on thermal flow microsensor. II. Flow meter,test procedures and results

A prototype of mass air flow meter for automobile industry was developed on the basis of thermal flow microsensor. Design and manufacturing technology of the flow meter are described. Test procedure and results are presented. Developed prototype of flow meter can diagnose gas flow rates in a wide range.     

峰流速仪标定系统数学模型的研究

对峄流速仪标定系统中的空气运动进行分析，引进特征线方法，建立了峰流速仪标定系统的数学模型，编制了计算机仿真程序，仿真结果与实验结果基本吻合，证明该模型的正确性。利用该模型对待标定的峰流速仪进行了标定。     

涡轮流量计在不同粘度介质下标定曲线形态的实验研究

涡轮流量计的准确度受被测介质及其运动粘度变化的影响。使用体积流量和仪表系数无法从变粘度实验中取得形态一致且可预测的标定结果。应用量纲分析导出雷诺数和斯特劳哈尔数作为描述涡轮流量计性能的无量纲参数。通过改变丙二醇-水溶液的体积浓度得到5个不同运动粘度的介质,分别用于标定一台DN25涡轮流量计。对比结果表明,不同粘度下的标定曲线在雷诺数小于7 400区域出现分离,标定数据最大相差0.9%。随着雷诺数增加,仪表系数中轴承阻滞部分的影响相对减小,标定曲线簇由分散趋于聚拢,标定数据差异小于0.1%。叶片表面的流动边界层发生层湍转捩时阻力的突变导致标定曲线出现驼峰,运动粘度越低,驼峰趋于平缓。轴承阻滞中的静态阻力部分是造成相同雷诺数下仪表系数差异的主要原因,这种差异随雷诺数减小而增加,所以,当校准介质和工作介质的运动粘度有显著差异时,涡轮流量计要避免工作在低雷诺数区域。     

差压式流量传感器测量一般气体流量时的温度压力补偿方法

简要介绍使用差压式流量传感器进行一般气体流量测量时的温压补偿方法;指出了差压方式流量传感器测量一般气体的通用流量温压补偿公式,并写出了公式的推导过程;与线性流量传感器温压补偿方法进行对比,强调指出了采用差压式流量传感器时进行温压补偿的注意要点.对公用工程中的一般气体的流量计量工作有一定的指导作用.     

Liquid hydrocarbon flow meters calibration with high flow and viscosity: Conceptual design of a new facility

The oil and natural gas production market is heavily regulated with specifications that are almost always defined and valid for each producing country. In all the focus is to ensure accurate and complete results in volumes produced but with specificities of each location. In Brazil this regulation was created in the year 2000 (Joint Ordinance No. 001 between the National Petroleum Agency - ANP and the National Institute of Metrology, Quality and Technology - INMETRO) and in the 2013 review it was specified that liquid hydrocarbon flow meters should be calibrated with fluid under the conditions closest to those found in the operation considering density, viscosity, flow, pressure and temperature. However, the type of oil produced in Brazilian fields typically has high viscosity and there is an additional aspect due to the use of FPSO (Floating Production Storage and Offloading) type production platforms: flow to tankers occurs at high flow rates. There are several restrictions in laboratories worldwide to meet these conditions (high viscosity with high flow) and so the purpose of this paper is to present a proposal that technically meets the conditions imposed by Brazilian regulations and that will serve as a reference for operations in other similar fields. The project considers the laboratory should be able to perform calibrations up to 3200 m^3/h, oil densities above 0.88, with flexibility for changing calibration fluid, pressure and temperature control and viscosities up to 700 cP. To this end, a broad evaluation was carried out with solution providers and a research group within the university to technical support     

Feasibility of using thermal response methods for nonintrusive compressed air flow measurement

Robust, low-cost nonintrusive flow meters are of interest in many industries. In particular, a reliable nonintrusive flow measurement for the diagnosis of air leaks in compressed air systems is desirable. Measurement of the air flow due to leaks in the system ensures an accurate estimation of potential cost and energy savings. This study evaluates a novel method of using thermal responses to nonintrusively measure leakage rates in compressed air lines. The method uses heat and the resulting thermal response to calculate the flow rate inside the compressed air line. Compared to the current methods for flow measurement, this method can simplify flow measurement while decreasing the sensitivity to errors when measuring flow rates. In this study, the methodology of the proposed method is explained along with the potential advantages to the design. Two approaches are evaluated: a dynamic step response and sinusoidal frequency response. Simulated tests evaluate the feasibility of the proposed methods, followed by experiments that validate the simulation results. A clear correlation between the thermal step response and the flow rate indicate viability of the proposed method in simulation. Experimental results yielded similar results, confirming the validity of the proposed method. The results of a field test in an industrial environment demonstrate the capability of the approach to other flow rate measurement techniques.